Launching into research
Large animal surgical resident Dr. Imma Roquet and one of her equine patients. Photo: Debra Marshall.
When Dr. Imma Roquet arrived at the Western College of Veterinary Medicine (WCVM) to begin her equine surgery residency in 2009, the Spanish veterinarian had never worked on a research project. But two years after meeting Dr. James Carmalt — a WCVM associate professor in large animal surgery and her residency supervisor — research has become a big part of Roquet’s life.
Today, Roquet is involved in several of Carmalt’s projects, and she admits that his enthusiasm for research has rubbed off on her: “Dr. Carmalt is a very active person in research — he likes to keep busy. He’s the reason I’ve become more interested in studying problems that we come up against while treating our patients.”
Does blood influence synovial fluid samples?
While Roquet is assisting Carmalt with two of his projects, she’s the key person on a study targeting the effect of blood contamination on parameters for equine synovial fluid. The project is part of Roquet’s Master of Veterinary Science (MVetSc) degree program that she’s completing in combination with her residency.
Synovial fluid is the clear liquid that serves as a lubricant in a horse’s joint, tendon sheath or bursa. Analyzing synovial fluid is a common procedure that veterinarians perform on horses to determine the presence or absence of septic synovitis – a severe, possibly life-threatening, infection of the joint. It’s crucial to diagnose and treat the condition early to improve the prognosis.
Roquet has seen a lot of traumatic joint injuries in horses brought to the WCVM Veterinary Medical Centre. The synovial fluid samples that she collects from her patients are often bloody, making it difficult to correctly diagnose septic synovitis.
“Horses don’t stay still like human patients. When you try to get a fluid sample from a horse, they often move and cause more trauma to the area which can lead to blood contamination,” she explains.
Roquet’s goal is to determine how much blood contamination influences synovial fluid parameters, including white blood cell count and total protein levels. Her findings may potentially aid in improving diagnostic accuracy, allowing veterinarians to design an appropriate treatment plan for their patients.
A tale of two grafts
Coronary band grafting, a surgical tissue graft procedure, is another study that caught Roquet’s interest. According to Roquet, it’s fairly common for horses to get heel bulb lacerations that may involve the coronary band and hoof. In the long term, the hoof may not grow normally depending on how extensively the coronary band is affected. Not only is it a cosmetic issue, but lameness usually results.
The investigation, which is supported by the Equine Health Research Fund (EHRF), looks at the effectiveness of two different types of grafts. An autograft is a tissue graft from the same horse and an allograft is a tissue graft from one horse to another. Researchers will compare these treatments to a third model in which the hoof defect is left empty.
“We hope to show that grafting will improve the healing and health of the hoof, reducing the risk of lameness,” explains Roquet, adding that the research is still in progress. The project’s five horses will be re-evaluated regularly throughout the rest of this year.
Testing pastern fracture treatments
This latest study, which received funding from the EHRF this year, began in May 2011. Roquet, along with Carmalt, will look at the optimal position and number of transcortical pins to be inserted into the cannon bone to repair fractures of the long pastern (P1) and the short pastern (P2) bones.
Fragmented fractures of P1 and P2 bones are difficult to repair with conventional plates and screws. The alternative is a transfixation pin cast that involves placing a metal pin implant through the cast, the cannon bone and soft tissues of the limb.
“Because horses need to immediately bear weight on their limb post-surgery, it’s important that pressure is removed from the bony column,” explains Roquet. The pin cast allows weight to be transmitted from the horse to the pins and cast, preventing the fractured bones from being crushed.
After two of the WCVM’s equine patients presented with fragmented phalangeal fractures (one with a fractured long pastern and the other with a fractured short pastern), Roquet started reviewing veterinary literature to find out what could be done for these horses.
“Many retrospective studies have been done on placement of transcortical pins, but no in vitro studies,” explains Roquet, adding that there are two general schools of thought on the position and number of pins used for the repair.
One method, described by renowned equine surgeon Dr. Larry Bramlage of Lexington, Ky., places four small diameter (4.8 millimetre) pins as distal as possible through the cannon bone (just above the fetlock joint). Other surgeons choose to place two large diameter (6.3 millimetre) pins through the cannon bone.
“Theoretically, the more pins and the bigger the pins, the less risk of crushing the fractured phalanges,” explains Roquet. “However, the bigger the pins, the weaker the cannon bone becomes.”
In the WCVM study, Roquet and Carmalt will use 30 forelimbs from equine cadavers to compare these two methods. A third method, where one large diameter pin is placed distal on the cannon bone and one placed in the middle of the bone shaft, will also be tested. Roquet hopes to determine which method works best to improve the prognosis of horses suffering from phalangeal fractures.
Since orthopedic surgery is one of Roquet’s main interests, she’s excited about working on the transfixation pin cast project. In fact, all of the research projects that Roquet has worked on with Carmalt have helped her gain a new appreciation for the world of research.
“Research is interesting and I’m glad to have had the chance to work on many different projects,” says Roquet. “I’ve worked with a lot of good people. It’s been a really great experience – both personally and professionally.”
Robyn Thrasher of Edmonton, Alta., is a second-year veterinary student at the WCVM. Robyn produced stories about the veterinary college’s research program and its researchers as part of her 2011 summer job in research communications.
